Archive for journalism

the limits of R

Posted in Books, pictures, R, Statistics with tags , , , , , , , , , , , , on August 10, 2020 by xi'an

It has been repeated many times on many platforms, the R (or R⁰) number is not a great summary about the COVID-19 pandemic, see eg Rossman’s warning in The Conversation, but Nature chose to stress it one more time (in its 16 Jul edition). Or twice when considering a similar piece in Nature Physics. As Boris Johnson made it a central tool of his governmental communication policy. And some mayors started asking for their own local R numbers! It is obviously tempting to turn the messy and complex reality of this planetary crisis into a single number and even a single indicator R<1, but it is unhelpful and worse, from the epidemiology models being wrong (or at least oversimplifying) to the data being wrong (i.e., incomplete, biased and late), to the predictions being wrong (except for predicting the past). Nothing outrageous from the said Nature article, pointing out diverse degrees of uncertainty and variability and stressing the need to immediately address clusters rather than using the dummy R. As an aside, the repeated use of nowcasting instead of forecasting sounds like a perfect journalist fad, given that it does not seem to be based on a different model of infection or on a different statistical technique. (There is a nowcasting package in R, though!) And a wee bit later I have been pointed out at an extended discussion of an R estimation paper on Radford Neal’s blog.

Bayes @ NYT

Posted in Books, Kids, Statistics, University life with tags , , , , , , , , , , , on August 8, 2020 by xi'an

A tribune in the NYT of yesterday on the importance of being Bayesian. When an epidemiologist. Tribune that was forwarded to me by a few friends (and which I missed on my addictive monitoring of the journal!). It is written by , a Canadian journalist writing about mathematics (and obviously statistics). And it brings to the general public the main motivation for adopting a Bayesian approach, namely its coherent handling of uncertainty and its ability to update in the face of new information. (Although it might be noted that other flavours of statistical analysis are also able to update their conclusions when given more data.) The COVID situation is a perfect case study in Bayesianism, in that there are so many levels of uncertainty and imprecision, from the models themselves, to the data, to the outcome of the tests, &tc. The article is journalisty, of course, but it quotes from a range of statisticians and epidemiologists, including Susan Holmes, whom I learned was quarantined 105 days in rural Portugal!, developing a hierarchical Bayes modelling of the prevalent  SEIR model, and David Spiegelhalter, discussing Cromwell’s Law (or better, humility law, for avoiding the reference to a fanatic and tyrannic Puritan who put Ireland to fire and the sword!, and had in fact very little humility for himself). Reading the comments is both hilarious (it does not take long to reach the point when Trump is mentioned, and Taleb’s stance on models and tails makes an appearance) and revealing, as many readers do not understand the meaning of Bayes’ inversion between causes and effects, or even the meaning of Jeffreys’ bar, |, as conditioning.

preprints promote confusion and distorsion, and don’t blame journalists!

Posted in Books, pictures, Travel, University life with tags , , , , , , , , on October 4, 2018 by xi'an

“…anyone considering publicizing a preprint have a responsibility.”

On my way to the airport, flying to B’ham, I read an older issue of Nature that contained this incredible editorial entry from Tom Sheldon Tim Horton, calling for regulation of preprints or worse, for the reason that journalists could misunderstand their contents and over-hype a minor or worse wrong claim. Taking as mistaken illustration the case of the Séralini et al. paper, about the Monsanto maize, which happened to be published under “embargo” conditions and reproduced in most media before a scientific storm erupted on the lack of significance of the samples. This call is unbelievably cheeky and downright absurd as it shifts the responsibility away from the journalists to the scientific community, throwing the “check your sources” principle of investigative journalism down the drain. As if the only reason for immediately publishing front-page discoveries is not to beat the competition and attract more readers…

The irony of seeing this piece in Nature is that a few pages later, there is a news entry on German and Swedish institutions breaking negotiations with Elsevier, as the publisher refuses to join a global package of open source publications. Nothing seems amiss about this nice aspect of scientific publishing with the author of this editorial, nor with the further reports of retraction of published paper in the same issue. Presumably because journalists have already moved to the next hot discovery by the time the retractions at last appear…! And to answer the final question of “Should all preprints be emblazoned with a warning aimed at journalists that work has not been peer reviewed?”, no, no, and no: preprints are not written for journalists or the general public. Unsurprisingly, the tribune induced outraged reactions from Nature readers.

a free press needs you [reposted]

Posted in Books, Kids with tags , , , , , , , on August 16, 2018 by xi'an

“Criticizing the news media — for underplaying or overplaying stories, for getting something wrong — is entirely right. News reporters and editors are human, and make mistakes. Correcting them is core to our job. But insisting that truths you don’t like are “fake news” is dangerous to the lifeblood of democracy. And calling journalists the “enemy of the people” is dangerous, period.”

weakonomics

Posted in Books, Statistics, University life with tags , , , , , , on February 4, 2013 by xi'an

Believe it or not, I had never read Freakonomics..! Therefore, when I saw the book on sale for a negligible price in Dehli Airport—great airport by the way!—, I went for it. Having now read a fair chunk of the book (or unfair chunk, see below!) within two days (during my metro rides), I am rather disappointed by the content and thus puzzled by the then-craze about the book. (Andrew just loved it!) Freakonomics is certainly a well-designed product from a salesman perspective and it thus reads pleasantly enough, but I find it remains at too much of a superficial level. In addition, it sometimes sounds as if the authors have a hidden agenda (more later)! (Now, of course, my reaction of the book is completely irrelevant as it comes very late after the publication in 2005. So, reader,  stop here if you do not want to waste time any further!)

“…if the death penalty were assessed to anyone carrying an illegal gun, and if the penalty were actually enforced, gun crimes would surely plunge.” (p.118)

To wit, the way the book is written sounds much more journalistic than academic: the authors take an economic study or paper about an unusual (freakish) topic and weave a nice story around it, always with the intent of showing “conventional wisdom” is wrong. Since this is a general public book, there is no theory behind the story and it all seems to flow from “common sense”: yes, most drug dealers do not earn enough to make a living because the corporate structure of the drug economy is highly hierarchical and as highly biased towards higher levels. The only foray into theory, namely the discussion about factors impacting kids success rate at school, casts doubts about regression and the distinction between causation and correlation is never truly investigated (even though the mantra correlation is not causation is found therein often enough!). Moreover, by resorting to the journalistic trick of making everything very personal (so-and-so went to drug dealer housing projects for six years, so-and-so decided to re-analyse the school records in Chicago, &tc.), the authors actually lower the credentials of their theories. If so-and-so found this effect, maybe there is another or an hundred others so-and-so going the opposite way! But those others are not mentioned as the book retains this flatland and Unitarian perspective… And the conclusions are anti-climactic: when so-and-so gets hold of the ledgers of a crack dealing gang, the description stops at reporting the hierarchical structure of the organisation and the revenues of the different levels. No major theory appears to be tested. At least within the book.

“Given the number of handguns in the United States (…), the probability that a particular gun was used to kill someone that year is 1 in 10,000. The typical gun buyback yields fewer than 1,000 guns—which translates into an expectation of less than one-tenth of one homicide per buyback.” (p.121)

The above quote puzzled me for a while, until I formalised the experiment as an hypergeometric draw of 1000 guns from a population of almost 300 millions guns, out of which more than 10,000 are crime guns. (The probability that a particular gun is used for a crime is then 1 in 30,000.) And the probability to draw at least one of those guns in one buyback is then approximately 0.03. But this seems to miss the other side of the equation, namely the worth of a human life. (Not that I believe that gun buybacks are particularly effective since, as noted by the authors, they mostly attract “heirldom or junk” (p.121).)

A minor disappointment was to stumble upon the conclusion of the book in…its very middle! I first thought I was confused and this was only the conclusion to a section but no, the second half of the book as I bought it was made of extracts from the authors’ column in the New York Time and of their blog, getting close to a swindle in my opinion! Or at least being the unfair chunk mentioned above. I also find annoying (and so does Andrew!) this insistence upon being rogue economists, as advertised on the front cover of the book, as the authors have shown themselves to be very efficient economists by turning the freakonomics idea into a whole business: books, films, videos, lectures, &tc. Nothing to complain about, except for the rogue label. (Note that they should have registered the franchise as well, given the subsequent profusion of -omics books and sites, from the fantastic Freakonometrics blog of my former colleague Arthur Charpentier, to Soccernomics I recently bought for my son…)